The invention relates to a micromanipulator, and more particularly, to a micromanipulator which enables a micromanipulation function of a microscope.
Current research of living cells in the medical and biological fields requires a micro-technique or micromanipulation such as a movement, transfer or shift on the order of several microns for various purposes such as removal of a nucleus from a cell, plantation of intra-cell structure, minute injection of enzyme or medicine into cells, or the determination of an electrical resistance of protoplasm. Other applications of a micromanipulation include the determination of the electrical conductivity of a metal crystal, the determination of elasticity of synthetic and natural fibres, assembly of very small mechanical parts, the manufacturing of large scale integrated circuits, the preparation of specimens for examination under microscope, and the isolation of rare elements such as plutonium.
Micromanipulation takes place by using a micromanipulator which includes a gearing and hydraulic assembly to convert a relatively coarse movement by hand into a minute movement. A miniature operating tool such as a miniature needle, micro-pippet, micro-electrode is attached to the manipulator, which is then operated to displace the miniature operating tool through a very small incremental distance so that the free end of a micro-pippet, for example, may be pierced into a cell to withdraw the nucleus thereof.
A conventional micromanipulator 1 is illustrated in FIG. 1. As shown, it comprises a stationary base 2 carrying an upstanding stanchion 3 on which a support member 4 is mounted. An angular position adjusting member 5 is secured to the support member 4 by means of an adjusting screw 4a, and fixedly carries a Z-axis translational member 6 which in turn fixedly carries a Y-axis translational member 7. An X-axis translational member 8 is mounted on the member 7. It is to be understood that each of the members 6 to 8 are capable of sliding movement relative to each other by an arrangement including a dovetail and dovetail groove combination and a rack and pinion combination. Operating knobs 5a, 6a, 7a are connected with these pinions to cause a rotation thereof so that the members 6, 7, 8 can be displaced in the directions of Z- Y- and X-axis. By choosing a suitable gear ratio between the racks and pinions or by using intermediate gears, a movement by hand which rotates the operating knobs 5a to 7a can be converted into a movement of the members 6 to 8 on the order of several microns. A mounting member 9 is fixedly mounted on the X-axis translational member 8, and a miniature operating tool 10 such as a needle, micro-pippet or miniature electrode is attached to the mounting member 9.
In operation, a specimen 12 such as cells is placed on a schale 11 or glass plate, which is then located centrally on a stage 14 of microscope 13. By adjusting a focussing knob 16 while viewing through an eyepiece 15, a lens barrel 18 including an objective lens 17 is moved vertically to bring a desired cell contained in the specimen 12 into the field of sight of the objective lens and to focus the latter thereon while simultaneously moving the schale 11. If required, a condenser 19 mounted on the stage 14 may be adjusted to control the brightness within the field of sight. Subsequently, the micromanipulator 1 is placed on a table 20 on which the microscope 13 is located so that the free end of the miniature operating tool 10 is located close to the specimen 12. If required, the screw 4a may be turned to adjust the angle of inclination of the tool 10. The knobs 5a to 7a are then turned to displace the tool 10 through minimal incremental distances in X, Y and Z-axis directions, respectively, to pierce the free end into a desired cell, thus effecting a micromanipulation.
With the conventional micromanipulator 1 described above, it is disposed outside the microscope 13, so that a microscope of the type which is fixedly mounted on a stage is preferred in that the elevation of the specimen 12 is fixed. However, the recent trend of microscopes which are used for biological purposes is toward that type having a fixed length of mechanical lens barrel and in which the focussing is achieved by vertically moving the stage. When the conventional micromanipulator is used in combination with the microscope of the type having a vertically movable stage, the stage must be moved vertically as is the location of specimen each time a focussing operation of the microscope takes place. Hence, in order to pierce the free end of the tool 10 into a desired cell, it is necessary to operate three knobs 5a to 7a to bring the free end of the tool 10 progressively closer to the cell while focussing the objective lens alternately on the free end of the tool 10 and the desired cell, by turning the focussing knob. In the process, it is to be noted that the miniature operating tool 10 is brought into the field of sight of the objective lens in an oblique direction which is close to the horizontal in order to avoid the interference of the tool 10 with the objective lens. This means that the X, Y and Z-axis along which the tool 10 is moved by operating the knobs 5a to 7a are different from the vertical direction, one horizontal direction and another horizontal direction which is perpendicular thereto. Thus, it becomes necessary to operate at least more than one knobs in order to move the free end of the tool 10 vertically relative to the specimen. Hence, a high degree of skill is required to pierce the free end of the tool 10 into a desired cell. Even a skilled operator is only capable of piercing into the order of 500 cells at most in one hour, for example.
The described disadvantage of using the manipulator with the microscope having a vertically movable stage can be overcome by placing the micromanipulator directly on the stage of the microscope. In actuality, a micromanipulator which may be placed on the stage is offered on the market. However the micromanipulator must be reduced in size to degrade the operating ease because of the requirements that the manipulator can be placed on the stage, the free end of the tool 10 can be pierced into a specimen and that no interference with a rotation of the revolver when the objective lens is mounted is avoided.
Even if a microscope having a fixed stage is used or micromanipulator is placed on the stage, there remains the disadvantage that the X-, Y- and Z-axes along which the tool 10 is moved are different from the vertical direction, and two mutually perpendicular horizontal directions as viewed through the microscope, thus requiring three knobs to be operated. Since the tool 10 must be introduced into the field of sight along a direction which is close to the horizontal, specimen 12 must be placed on flat schale 11 or a glass plate, which causes a rapid evaporation of moisture contained in the specimen 12, which is dried up in a short period of time to destroy the cells contained therein.